X-ray catheter



Oct. 28, 1958 D. s. SHERIDAN 2,857,915

X-RAY CATHETER Filed April 2, 1956 INVENTOR DAVID S. SHERIDAN BY fiwm ATTORNEY United States Patent X-RAY CATHETER David S. Sheridan, Argyle, N. Y.

Application April 2, 1956, Serial No. 575,393

Claims. (Cl. 128-349) This invention relates to X-ray catheters, i. e., nonabsorptive catheters whose position within living tissue into which the catheter is inserted may be determined by X-ray observation.

In many of the surgical or clinical procedures in which catheters are employed, it is desirable or even essential to be able to determine the location of the distal end or other portion of the catheter within the body of a patient into which it has been inserted. This determination can be made in several ways, but one of the most satisfactory methods employs X-ray observation. This is accomplished by using a catheter which is in whole or in part opaque to X-rays and directing a beam of X-rays through the body of the patient in the neighborhood of the inserted catheter while observing the relative positions of catheter and living tissue on a fluoroscope or X-ray film.

Several forms of catheters have been devised and manufactured heretofore to be used With such X-ray observation procedures. One type is made by making lines or markings with a fine brush, stenciling devices, printing equipment, or the like, on an X-ray transparent, preformed catheter, using an X-ray opaque paint or coating composition to form the markings. However, the most prevalent type of X-ray catheter is completely opaque to both visible light and to X-rays and such catheters can be made by incorporating an X-ray opaque substance in the material which makes up the entire wall of the tube. Likewise, X-ray catheters have been prepared by using varnish or other coating compositions which have X-ray opaque pigments dispersed therein to form one or more layers of the catheters. In this case, the resulting catheters are generally opaque, both to visible light and X-rays throughout their entire length and cross-section.

X-ray catheters have also been produced as described in U. S. Patent 2,212,334 by extruding a plastic cellulosic material through a tubular molding die and at uniform brief intervals, forceably injecting into the stream of the extruded material as it is being molded, a small quantity of similar plastic material impregnated with X-ray opaque material. This forms a catheter having a series of separated X-ray opaque marks extending longitudinally along the catheter.

Although the Xray catheters known and made heretofore have been generally useful for their intended purposes, they have also had certain inherent deficiencies which have prevented their use from being completely satisfactory. For example, this type of catheter which is made by having the X-ray opaque markings painted thereon or by including X-ray opaque material in the varnish or coating compositions used in forming outer layers of the catheters do not stand up well in use because when subjected to sterilization or cleaning, the markings or coatings are in whole or in part destroyed. Also with some known catheters of the X-ray type there has been a problem of precisely defining their position when observed by X-rays because there are portions of such catheters which are not opaque, e. g., the distal end, which may be folded back or bent in a harmful manner without showing up on the X-ray screen. Furthermoreflt is important to have a uniform X-ray shadow show up. so as not to confuse the physician with a broken line, especially with uretheral catheters where small kidney stones might be hidden behind or mistaken for a sepa rate marking.

A principal object of the present invention is to provide X-ray catheters of a new, improved type. Further objects include:

(1) The provision of new, non-absorptive catheters, Which for the most part are transparent to visible light so that it is possible to see through them to ascertain their cleanliness or the like, but which have an integral continuous opaque strip or line running along the entire length of the catheter so as to permit the position of each and every portion of the catheter to be precisely determined within living tissue into which the catheter may be inserted by X-ray observation;

(2) The provision of X-ray catheters which have substantially uniform wall thickness throughout their entire length, but at the same time are double tapered, i. e., have a distal end which tapers down to a small blunt tip and have a rear or outlet end which flairs outwardly to a diameter substantially larger than the diameter of the principal untapered section of the catheter.

Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter; it should be understood, however, that the detailed description, while indicating preferred embodiments of the invention, is given by way of illustration only, since various changes and modifications Within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

A more complete understanding of the new catheters of this invention and their method of production can be had by reference to the accompanying drawing in which:

Fig. 1 is a plan view of one form of catheter made in accordance with the present invention;

Fig. 2 is an enlarged cross-sectional view of the catheter of Fig. 1, taken along the line 2-2 of Fig. l; I

Fig. 3 is an enlarged cross-sectional view of an extension die used to form the new catheters.

Referring in detail to the drawings, the catheter 2 comprises a generally circular, seamless, non-fibrous tube 4 which tapers down from a main body section 6 of substantially uniform cross-section at the probe or distal end 8 to a tip 10. The funnel or trailing end 12 of the tube 4 flairs or tapers outwardly so that the open end 14 is of substantially larger diameter than the main body portion 6.

One or more inlet openings 16 are provided in the distal end 8 through which fluids may enter the catheter to be conducted through the tube 4 and out the opening 14, or as is known, the funnel end 12 may be attached to a syringe to inject fluids into the patient.

A strip or line 18 runs longitudinally along the entire length of the tube 4 and, as can be seen in Fig. 2, this line is formed by a strip of material which is integral with and embedded in the tube 4, so that the outside 20 and inside 22 of the tube are completely smooth. i

The tube 4 is made from flexible water-proof plastic material and a variety of products are commercially available for this purpose. Examples of usable materials include certain pliable or flexible forms of nylon; polyester plastics; polyethylene; and vinyl polymers, such as vinyl chloride polymers or copolymers with other vinyl esters such as vinyl acetate; vinylidene chloride polymers or the like.

Although it is possible to include X-ray transparent pigment in the plastic material of which tube 4 is formed,

Patented Oct. 28, 8

it i preferable that the plastic material. be unpismeut d so that it is transparent to visible light, making it possible to see through the catheter, to determine if it is clean, or to determine. position of foreign, matter or the like that. might beinit. Ifdesi'red, dyes; can be in.- cluded in, the plastic material to give the catheter a dis;- tinctive color, thus marking it for special uses or other purposes.

Although it is possible: to form the. strip: 1.8 from plastic; material which is compatible with, although chemically difierent from a plastic: material used tov form the main tube 4, this stripv 18' is preferably made from the same plastic material as the tube 4. However, in. the plastic; of; which the strip. 18: is composed, there: is uniformly dispersed a finely powdered X-ray opaquev pigment. Obviously, this pigment should: bev water insoluble and non- Various; materials are available for this purpose, such as. insoluble organic iodine containing compounds, but preferably a bismuth salt is used, e. g., bismuth subnitrate or bismuth oxide.

1 The new catheters are made by: an extrusion procedure. Thus, a bi-orifice tubularextrusion die, such as shown in Fig. 3, is fitted to a double screw extrusion machine or similar device equipped with means for blowing air into the resulting extruded tube through acentral opening 26 in the center of the die 24'. The tubular die 24 has a major orifice 28 which is substantially ring-shaped in cross-section, formed between the inner wall 30 and outer wall 32, and also has a minor orifice 34 which is substantially circularly segmental in cross-section, formed by anarcuate-wa'll portion 36' anda chordal wall portion 38 contiguous with the outer wall 32 of the major orifice 28.

In extruding the tube of which the catheter is formed, the plastic material tocreate the tube 4 is extruded through themajor orifice 28-, while the X-ray opaque pigmented plastic material to form the longitudinal strip 18 is extruded through the minor orifice 34.

With the possible exception of that part of the catheter which comprises the tip 1 0 of the catheter, the catheter should have substantially'a uniform wall thickness throughoutits length. Such uniformity in wall? thickness, in spite of-the tapered ends 8 and 12, is obtained by extrudin'g plastic material through the die 24 in varying quantities per unit time, and at the same time, coordinating the rate of withdrawing the tube away from the die, and also introducing air through the die opening 26, so that the air blowing and withdrawal is coordinated with the change in rate of extrusion of plastic material to maintain a substantially constant wall thickness with varying diameter of tubing.

The-tubing as it' is withdrawn from the extrusion die, can immediately be cut into proper lengths at the points of maximum and minimum taper, or a' continuous length of tapered tubing can be produced from which catheters can subsequently be formed by a series of operations in which the continuous tubing is cut at the points of maximum diameter and then cut at the points of minimum diameter, if open. end catheters; are desired, or heated at these points of minimum diameter so as to close the end of the tube and form a: closed tip 10 if a closed end catheter is required. Thereafter, the required number of inlet openings 16 can be. punched, drilled or melted into the catheter.

The new catheters. of this invention can be used. as roughly or treated as severely as most any other catheters no av ilabl witho t de m nt t the X-r y marked characteristics thereof. Moreover, they can be made not only as double-taper catheters as specifically described and illustrated, but in any other standard shapes or forms in which catheters are produced.

I claim:

1. A non-absorptive catheter whose position within living tissue into which the catheter is inserted may be precisely determined by X-ray observation which consists of a seamless, non-fibrous tube of flexible, waterproof, plastic material having a continuous strip of said plastic material with powdered X-ra-y opaque pigment dispersed therein extending. longitudinally along the entire length thereof, said strip being integral with and embedded in the remainder of the tube, whereby said tube has substantially smooth inner and outer surfaces.

2. A non-absorptive catheter whose position within living tissue into which the catheter is inserted may be preci'sely determined by X-ray observation which consists of a. seamless extruded tube of a vinyl chloride copolymer of substantially uniform thickness throughout, having a continuous strip of'sai'd copolymer with apowdered waterinsoluble bismuth salt pigment dispersed therein extending longitudinally along the entire length thereof, said strip being integral with and embedded in the remainder of the tube whereby said tube has substantially smooth inner and outer surfaces.

3-. A catheter as claimed in claim 1 wherein. said tube, exclusive of said pigmented strip, is transparent both to X-rays and visible light.

4. A non-absorptive catheter whose position within living tissue into which the catheter is inserted may be precisely determined by X-ray' observation whichconsists of an extruded, seamless, non-fibrous tube of flexible, water-proof, plastic material having a continuous strip of X-ray opaque material extending longitudinally along the entire length thereof, said strip being integral with and embedded in the remainder of the tube, whereby said tube has substantially smooth inner and outer surfaces.

5. A non-absorptive catheter whose position Within living tissue into which the catheter is inserted may be precisely determined by X-ray observation which consists of an extruded, seamless-,non-fibrous tube of flexible, waterproof, plastic material having a' continuous strip of X-ray opaque material extending longitudinally along the entire length thereof, said strip being integral with and embedded in the remainder of the tube, whereby said tube has substantially smooth inner and outer surfaces and said tube, exclusive of said X-ray strip, being transparent both to X'-rays and visible light.

ReferencesCitedin the file of. this patent UNITED STATES PATENTS 1,428,381 Lower Sept. 5, 1922 2,212,334 Wallereich Aug. 20, I940 2,561,569 Flynn July 24, 1951 2,688,329 Wallace Sept. 7-, 1954 FOREIGN PATENTS 726,706 Great Britain Mar. 23, I955 REFERENCES Urological Instruments, Eynard, Catalog of C. R. Bard, Inc., Jan. 26', 1940;, page one, #370. (Copy in Division 55.) 

